(x) barley (Hordeum vulgare L.);] 2[3[(ia)] coal, including coke in all its forms, but excluding charcoal: Provided that during the period commencing on the 23rd day of February, 1967 and ending with the date of commencement of section 11 of the Central Sales Tax (Amendment) Act, 1972 (61 of 1972) this clause shall have effect subject to the modification that the words “but excluding charcoal” shall be omitted;]